Safe Haskell	None
Language	Haskell2010

Control.Effect.Choose

Contents

Choose effect
Choosing semigroup
Re-exports

Description

An effect modelling nondeterminism without failure (one or more successful results).

The NonDet effect is the composition of Choose and Empty.

Predefined carriers:

Control.Carrier.Choose.Church.
If Choose is the last effect in a stack, it can be interpreted directly to a NonEmpty.

Since: 1.0.0.0

Synopsis

data Choose (m :: Type -> Type) k where
- Choose :: Choose m Bool
(<|>) :: Has Choose sig m => m a -> m a -> m a
optional :: Has Choose sig m => m a -> m (Maybe a)
many :: Has Choose sig m => m a -> m [a]
some :: Has Choose sig m => m a -> m [a]
some1 :: Has Choose sig m => m a -> m (NonEmpty a)
newtype Choosing m a = Choosing {
- getChoosing :: m a
}
class Monad m => Algebra sig m | m -> sig
type Has eff sig m = (Members eff sig, Algebra sig m)
run :: Identity a -> a

Choose effect

data Choose (m :: Type -> Type) k where Source #

Since: 1.0.0.0

Constructors

Choose :: Choose m Bool

Instances

Algebra Choose NonEmpty Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n NonEmpty -> Choose n a -> ctx () -> NonEmpty (ctx a) Source #
Algebra NonDet [] Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n [] -> NonDet n a -> ctx () -> [ctx a] Source #
Algebra sig m => Algebra (Choose :+: sig) (ChooseC m) Source #
Instance details Defined in Control.Carrier.Choose.Church Methods alg :: Functor ctx => Handler ctx n (ChooseC m) -> (Choose :+: sig) n a -> ctx () -> ChooseC m (ctx a) Source #
Algebra sig m => Algebra (NonDet :+: sig) (NonDetC m) Source #
Instance details Defined in Control.Carrier.NonDet.Church Methods alg :: Functor ctx => Handler ctx n (NonDetC m) -> (NonDet :+: sig) n a -> ctx () -> NonDetC m (ctx a) Source #
Algebra sig m => Algebra (Cut :+: (NonDet :+: sig)) (CutC m) Source #
Instance details Defined in Control.Carrier.Cut.Church Methods alg :: Functor ctx => Handler ctx n (CutC m) -> (Cut :+: (NonDet :+: sig)) n a -> ctx () -> CutC m (ctx a) Source #
Algebra sig m => Algebra (Cull :+: (NonDet :+: sig)) (CullC m) Source #
Instance details Defined in Control.Carrier.Cull.Church Methods alg :: Functor ctx => Handler ctx n (CullC m) -> (Cull :+: (NonDet :+: sig)) n a -> ctx () -> CullC m (ctx a) Source #

(<|>) :: Has Choose sig m => m a -> m a -> m a infixl 3 Source #

Nondeterministically choose between two computations.

(m <|> n) >>= k = (m >>= k) <|> (n >>= k)

(m <|> n) <|> o = m <|> (n <|> o)

empty <|> m = m

m <|> empty = m

Since: 1.0.0.0

optional :: Has Choose sig m => m a -> m (Maybe a) Source #

Select between Just the result of an operation, and Nothing.

optional empty = pure Nothing

optional (pure a) = pure (Just a)

Since: 1.0.0.0

many :: Has Choose sig m => m a -> m [a] Source #

Zero or more.

many m = some m <|> pure []

Since: 1.0.0.0

some :: Has Choose sig m => m a -> m [a] Source #

One or more.

some m = (:) <$> m <*> many m

Since: 1.0.0.0

some1 :: Has Choose sig m => m a -> m (NonEmpty a) Source #

One or more, returning a NonEmpty list of the results.

some1 m = (:|) <$> m <*> many m

Since: 1.0.0.0

Choosing semigroup

newtype Choosing m a Source #

Since: 1.0.0.0

Constructors

Choosing
Fields getChoosing :: m a

Instances

Has Choose sig m => Semigroup (Choosing m a) Source #
Instance details Defined in Control.Effect.Choose Methods (<>) :: Choosing m a -> Choosing m a -> Choosing m a # sconcat :: NonEmpty (Choosing m a) -> Choosing m a # stimes :: Integral b => b -> Choosing m a -> Choosing m a #
(Has Choose sig m, Has Empty sig m) => Monoid (Choosing m a) Source #
Instance details Defined in Control.Effect.Choose Methods mempty :: Choosing m a # mappend :: Choosing m a -> Choosing m a -> Choosing m a # mconcat :: [Choosing m a] -> Choosing m a #

Re-exports

class Monad m => Algebra sig m | m -> sig Source #

The class of carriers (results) for algebras (effect handlers) over signatures (effects), whose actions are given by the alg method.

Since: 1.0.0.0

Minimal complete definition

alg

Instances

Algebra Choose NonEmpty Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n NonEmpty -> Choose n a -> ctx () -> NonEmpty (ctx a) Source #
Algebra Empty Maybe Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n Maybe -> Empty n a -> ctx () -> Maybe (ctx a) Source #
Algebra NonDet [] Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n [] -> NonDet n a -> ctx () -> [ctx a] Source #
Algebra sig m => Algebra sig (Alt m) Source #	This instance permits effectful actions to be lifted into the `Alt` monad, which eases the invocation of repeated alternation with `<\|>`: a <\|> b <\|> c <\|> d is equivalent to getAlt (mconcat [a, b, c, d]) Since: 1.0.1.0
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n (Alt m) -> sig n a -> ctx () -> Alt m (ctx a) Source #
Algebra sig m => Algebra sig (Ap m) Source #	This instance permits effectful actions to be lifted into the `Ap` monad given a monoidal return type, which can provide clarity when chaining calls to `mappend`. mappend <$> act1 <> (mappend <$> act2 <> act3) is equivalent to getAp (act1 <> act2 <> act3) Since: 1.0.1.0
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n (Ap m) -> sig n a -> ctx () -> Ap m (ctx a) Source #
Algebra sig m => Algebra sig (IdentityT m) Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n (IdentityT m) -> sig n a -> ctx () -> IdentityT m (ctx a) Source #
Algebra (Lift IO) IO Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n IO -> Lift IO n a -> ctx () -> IO (ctx a) Source #
Algebra (Lift Identity) Identity Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n Identity -> Lift Identity n a -> ctx () -> Identity (ctx a) Source #
Monad m => Algebra (Lift m) (LiftC m) Source #
Instance details Defined in Control.Carrier.Lift Methods alg :: Functor ctx => Handler ctx n (LiftC m) -> Lift m n a -> ctx () -> LiftC m (ctx a) Source #
Algebra (Error e) (Either e) Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n (Either e) -> Error e n a -> ctx () -> Either e (ctx a) Source #
Monoid w => Algebra (Writer w) ((,) w) Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n ((,) w) -> Writer w n a -> ctx () -> (w, ctx a) Source #
Algebra (Reader r) ((->) r :: Type -> Type) Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n ((->) r) -> Reader r n a -> ctx () -> r -> ctx a Source #
Algebra sig m => Algebra (Choose :+: sig) (ChooseC m) Source #
Instance details Defined in Control.Carrier.Choose.Church Methods alg :: Functor ctx => Handler ctx n (ChooseC m) -> (Choose :+: sig) n a -> ctx () -> ChooseC m (ctx a) Source #
Algebra sig m => Algebra (Empty :+: sig) (MaybeT m) Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n (MaybeT m) -> (Empty :+: sig) n a -> ctx () -> MaybeT m (ctx a) Source #
Algebra sig m => Algebra (Empty :+: sig) (EmptyC m) Source #
Instance details Defined in Control.Carrier.Empty.Maybe Methods alg :: Functor ctx => Handler ctx n (EmptyC m) -> (Empty :+: sig) n a -> ctx () -> EmptyC m (ctx a) Source #
Algebra sig m => Algebra (Empty :+: sig) (EmptyC m) Source #
Instance details Defined in Control.Carrier.Empty.Church Methods alg :: Functor ctx => Handler ctx n (EmptyC m) -> (Empty :+: sig) n a -> ctx () -> EmptyC m (ctx a) Source #
Algebra sig m => Algebra (NonDet :+: sig) (NonDetC m) Source #
Instance details Defined in Control.Carrier.NonDet.Church Methods alg :: Functor ctx => Handler ctx n (NonDetC m) -> (NonDet :+: sig) n a -> ctx () -> NonDetC m (ctx a) Source #
(MonadIO m, Algebra sig m) => Algebra (Trace :+: sig) (TraceC m) Source #
Instance details Defined in Control.Carrier.Trace.Printing Methods alg :: Functor ctx => Handler ctx n (TraceC m) -> (Trace :+: sig) n a -> ctx () -> TraceC m (ctx a) Source #
Algebra sig m => Algebra (Trace :+: sig) (TraceC m) Source #
Instance details Defined in Control.Carrier.Trace.Ignoring Methods alg :: Functor ctx => Handler ctx n (TraceC m) -> (Trace :+: sig) n a -> ctx () -> TraceC m (ctx a) Source #
Algebra sig m => Algebra (Trace :+: sig) (TraceC m) Source #
Instance details Defined in Control.Carrier.Trace.Returning Methods alg :: Functor ctx => Handler ctx n (TraceC m) -> (Trace :+: sig) n a -> ctx () -> TraceC m (ctx a) Source #
Algebra sig m => Algebra (Fail :+: sig) (FailC m) Source #
Instance details Defined in Control.Carrier.Fail.Either Methods alg :: Functor ctx => Handler ctx n (FailC m) -> (Fail :+: sig) n a -> ctx () -> FailC m (ctx a) Source #
Algebra sig m => Algebra (Fresh :+: sig) (FreshC m) Source #
Instance details Defined in Control.Carrier.Fresh.Strict Methods alg :: Functor ctx => Handler ctx n (FreshC m) -> (Fresh :+: sig) n a -> ctx () -> FreshC m (ctx a) Source #
Algebra sig m => Algebra (Fresh :+: sig) (FreshC m) Source #
Instance details Defined in Control.Carrier.Fresh.Church Methods alg :: Functor ctx => Handler ctx n (FreshC m) -> (Fresh :+: sig) n a -> ctx () -> FreshC m (ctx a) Source #
Algebra sig m => Algebra (Cut :+: (NonDet :+: sig)) (CutC m) Source #
Instance details Defined in Control.Carrier.Cut.Church Methods alg :: Functor ctx => Handler ctx n (CutC m) -> (Cut :+: (NonDet :+: sig)) n a -> ctx () -> CutC m (ctx a) Source #
Algebra sig m => Algebra (Cull :+: (NonDet :+: sig)) (CullC m) Source #
Instance details Defined in Control.Carrier.Cull.Church Methods alg :: Functor ctx => Handler ctx n (CullC m) -> (Cull :+: (NonDet :+: sig)) n a -> ctx () -> CullC m (ctx a) Source #
Algebra sig m => Algebra (Reader r :+: sig) (ReaderC r m) Source #
Instance details Defined in Control.Carrier.Reader Methods alg :: Functor ctx => Handler ctx n (ReaderC r m) -> (Reader r :+: sig) n a -> ctx () -> ReaderC r m (ctx a) Source #
Algebra sig m => Algebra (State s :+: sig) (StateT s m) Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n (StateT s m) -> (State s :+: sig) n a -> ctx () -> StateT s m (ctx a) Source #
Algebra sig m => Algebra (State s :+: sig) (StateT s m) Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n (StateT s m) -> (State s :+: sig) n a -> ctx () -> StateT s m (ctx a) Source #
Algebra sig m => Algebra (State s :+: sig) (StateC s m) Source #
Instance details Defined in Control.Carrier.State.Strict Methods alg :: Functor ctx => Handler ctx n (StateC s m) -> (State s :+: sig) n a -> ctx () -> StateC s m (ctx a) Source #
Algebra sig m => Algebra (State s :+: sig) (StateC s m) Source #
Instance details Defined in Control.Carrier.State.Lazy Methods alg :: Functor ctx => Handler ctx n (StateC s m) -> (State s :+: sig) n a -> ctx () -> StateC s m (ctx a) Source #
Algebra sig m => Algebra (State s :+: sig) (StateC s m) Source #
Instance details Defined in Control.Carrier.State.Church Methods alg :: Functor ctx => Handler ctx n (StateC s m) -> (State s :+: sig) n a -> ctx () -> StateC s m (ctx a) Source #
Algebra sig m => Algebra (Throw e :+: sig) (ThrowC e m) Source #
Instance details Defined in Control.Carrier.Throw.Either Methods alg :: Functor ctx => Handler ctx n (ThrowC e m) -> (Throw e :+: sig) n a -> ctx () -> ThrowC e m (ctx a) Source #
Algebra sig m => Algebra (Error e :+: sig) (ExceptT e m) Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n (ExceptT e m) -> (Error e :+: sig) n a -> ctx () -> ExceptT e m (ctx a) Source #
Algebra sig m => Algebra (Error e :+: sig) (ErrorC e m) Source #
Instance details Defined in Control.Carrier.Error.Either Methods alg :: Functor ctx => Handler ctx n (ErrorC e m) -> (Error e :+: sig) n a -> ctx () -> ErrorC e m (ctx a) Source #
Algebra sig m => Algebra (Error e :+: sig) (ErrorC e m) Source #
Instance details Defined in Control.Carrier.Error.Church Methods alg :: Functor ctx => Handler ctx n (ErrorC e m) -> (Error e :+: sig) n a -> ctx () -> ErrorC e m (ctx a) Source #
(Algebra sig m, Monoid w) => Algebra (Writer w :+: sig) (WriterT w m) Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n (WriterT w m) -> (Writer w :+: sig) n a -> ctx () -> WriterT w m (ctx a) Source #
(Algebra sig m, Monoid w) => Algebra (Writer w :+: sig) (WriterT w m) Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n (WriterT w m) -> (Writer w :+: sig) n a -> ctx () -> WriterT w m (ctx a) Source #
(Monoid w, Algebra sig m) => Algebra (Writer w :+: sig) (WriterC w m) Source #
Instance details Defined in Control.Carrier.Writer.Strict Methods alg :: Functor ctx => Handler ctx n (WriterC w m) -> (Writer w :+: sig) n a -> ctx () -> WriterC w m (ctx a) Source #
(Algebra sig m, Monoid w) => Algebra (Writer w :+: sig) (WriterC w m) Source #
Instance details Defined in Control.Carrier.Writer.Church Methods alg :: Functor ctx => Handler ctx n (WriterC w m) -> (Writer w :+: sig) n a -> ctx () -> WriterC w m (ctx a) Source #
(Reifies s (Interpreter eff m), Algebra sig m) => Algebra (eff :+: sig) (InterpretC s eff m) Source #
Instance details Defined in Control.Carrier.Interpret Methods alg :: Functor ctx => Handler ctx n (InterpretC s eff m) -> (eff :+: sig) n a -> ctx () -> InterpretC s eff m (ctx a) Source #
Algebra sig m => Algebra (Reader r :+: sig) (ReaderT r m) Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n (ReaderT r m) -> (Reader r :+: sig) n a -> ctx () -> ReaderT r m (ctx a) Source #
(LabelledMember label sub sig, Algebra sig m) => Algebra (sub :+: sig) (UnderLabel label sub m) Source #
Instance details Defined in Control.Effect.Labelled Methods alg :: Functor ctx => Handler ctx n (UnderLabel label sub m) -> (sub :+: sig) n a -> ctx () -> UnderLabel label sub m (ctx a) Source #
(Algebra sig m, Monoid w) => Algebra (Reader r :+: (Writer w :+: (State s :+: sig))) (RWST r w s m) Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n (RWST r w s m) -> (Reader r :+: (Writer w :+: (State s :+: sig))) n a -> ctx () -> RWST r w s m (ctx a) Source #
(Algebra sig m, Monoid w) => Algebra (Reader r :+: (Writer w :+: (State s :+: sig))) (RWST r w s m) Source #
Instance details Defined in Control.Algebra Methods alg :: Functor ctx => Handler ctx n (RWST r w s m) -> (Reader r :+: (Writer w :+: (State s :+: sig))) n a -> ctx () -> RWST r w s m (ctx a) Source #
Algebra (eff :+: sig) (sub m) => Algebra (Labelled label eff :+: sig) (Labelled label sub m) Source #
Instance details Defined in Control.Effect.Labelled Methods alg :: Functor ctx => Handler ctx n (Labelled label sub m) -> (Labelled label eff :+: sig) n a -> ctx () -> Labelled label sub m (ctx a) Source #

type Has eff sig m = (Members eff sig, Algebra sig m) Source #

m is a carrier for sig containing eff.

Note that if eff is a sum, it will be decomposed into multiple Member constraints. While this technically allows one to combine multiple unrelated effects into a single Has constraint, doing so has two significant drawbacks:

Due to a problem with recursive type families, this can lead to significantly slower compiles.
It defeats ghc’s warnings for redundant constraints, and thus can lead to a proliferation of redundant constraints as code is changed.

Since: 1.0.0.0

run :: Identity a -> a Source #

Run an action exhausted of effects to produce its final result value.

Since: 1.0.0.0